The frozen plains of northern Siberia's tundra have been pretty weird over the past couple of years - scientists have spotted giant holes appearing seemingly out of nowhere, and a giant chasm opened up that locals call the "gateway to the underworld".

But now local media has reported that the land has literally started bubbling beneath people's feet on Siberia's remote Belyy Island.

A video just released by the Siberian Times shows a researcher stepping on what looks to be a normal patch of grass - until it starts bizarrely wobbling like jelly. You can check it out for yourself below:

Environmental researchers Alexander Sokolov and Dorothee Ehrich first spotted the bubbles last year. They've been working on the island in the Kara Sea for years, as it's a popular place to monitor climate change thanks to its large polar bear population.

But they stumbled across the blister-like bubbles purely by accident, and were surprised to find them there again this year.

On their latest expedition, they've stripped the grass and dirt from one of these bubbles and recorded the escaping air, showing that it contains around 200 times more methane than normal air, and 20 times more carbon dioxide.

So what's going on here? More research needs to be done, but one hypothesis is that Europe's recent heatwave caused the tundra's permafrost to thaw, releasing methane gas just below the surface.

"It is likely that that 10 days of extraordinary heat could have started some mechanisms, [and the] higher level of permafrost could have thawed and released a huge amount of gases," Sokolov told the Siberian Times.

"Geologists suppose that there might be some gas leaking from the underground but it's unlikely. There is solid permafrost under the bubbles."

What's more worrying is that there's concern that all this newly released methane will actually exacerbate global warming further, with one study estimating that by 2100, up to 205 billion tonnes of carbon emissions will be released by permafrost if climate change continues to intensify, as Sarah Emerson reports for Motherboard.